where \(v=246\)  GeV is the Higgs vacuum expectation value.
If we neglect quantum effects captured by running the renormalization group equations, \(m_{eff}\)  does not change with the energy scale.
However, if we want to reproduce the masses of the active neutrinos to be in the eV region, as constrained by experiments, the masses of \(M_R\)  are required to be near the GUT scale.
This means for practical experiments the right-handed neutrinos are integrated out, down to the energy scale being considered [1]}, [2]}.
After integration, the Wilson coefficient of the so-called Weinberg operator, \(\kappa (\mu )\) , is generated [3]}.
\(\mathcal {O}_5 = \frac{1}{4} \kappa _{gh}^{\ast }(\mu )\left(\overline{l^C_L}^{\,g}\cdot \phi \right) \left(l^h_L\cdot \phi \right)+\text{h.c.}\) 
